Traditional transducer apparatus derives power from a battery source and requires an on/off switch to control the power supplied to the apparatus. The objective of the invention is to develop an automobile display apparatus to derive power from the cigarette lighter and for the power of the display apparatus to be switched on and off according to the motion and ambient light of the vehicle. A further objective of the invention is to design the display apparatus such that it can be detached from the motor vehicle and to be used as a portable warning signal lighting apparatus by night time.